Encapsulation of a TRPM8 Agonist, WS12, in Lipid Nanocapsules Potentiates PC3 Prostate Cancer Cell Migration Inhibition through Channel Activation.

In prostate carcinogenesis, expression and/or activation of the Transient Receptor Potential Melastatin 8 channel (TRPM8) was shown to block in vitro Prostate Cancer (PCa) cell migration. Because of their localization at the plasma membrane, ion channels, such as TRPM8 and other membrane receptors, are promising pharmacological targets. The aim of this study was thus to use nanocarriers encapsulating a TRPM8 agonist to efficiently activate the channel and therefore arrest PCa cell migration. To achieve this goal, the most efficient TRPM8 agonist, WS12, was encapsulated into Lipid NanoCapsules (LNC). The effect of the nanocarriers on channel activity and cellular physiological processes, such as cell viability and migration, were evaluated in vitro and in vivo. These results provide a proof-of-concept support for using TRPM8 channel-targeting nanotechnologies based on LNC to develop more effective methods inhibiting PCa cell migration in zebrafish xenograft.

Carbon nanowalls: a new versatile graphene based interface for the laser desorption/ionization-mass spectrometry detection of small compounds in real samples.

Carbon nanowalls, vertically aligned graphene nanosheets, attract attention owing to their tunable band gap, high conductivity, high mechanical robustness, high optical absorbance and other remarkable properties. In this paper, we report for the first time the use of hydrophobic boron-doped carbon nanowalls (CNWs) for laser desorption/ionization of small compounds and their subsequent detection by mass spectrometry (LDI-MS). The proposed method offers sensitive detection of various small molecules in the absence of an organic matrix. The CNWs were grown by microwave plasma enhanced chemical vapor deposition (MW-PECVD), using a boron-carbon gas flow ratio of 1200 in H2/CH4 plasma, on silicon <100> wafer. The hydrophobicity of the surface offers a straightforward MS sample deposition, consisting of drop casting solutions of analytes and drying in air. Limits of detection in the picomolar and femtomolar ranges (25 fmol µL-1 for neurotensin) were achieved for different types of compounds (fatty acids, lipids, metabolites, saccharides and peptides) having clinical or food industry applications. This rapid and sensitive procedure can also be used for quantitative measurements without internal standards with RSDs <19%, as in the case of glucose in aqueous solutions (LOD = 0.32 ± 0.02 pmol), blood serum or soft drinks. Moreover, melamine (63 ± 8.19 ng µL-1), a toxic compound, together with creatinine and paracetamol, was detected in urine samples, while lecithin was detected in food supplements.

Revealing the structure and functionality of graphene oxide and reduced graphene oxide/pyrene carboxylic acid interfaces by correlative spectral and imaging analysis.

A high-end correlated spectral and imaging multianalysis, adapted for bidimensional systems, is presented here to analyze graphene oxide (GO) and reduced GO (rGO) modified with pyrene carboxylic acid (PCA). Confocal Raman mapping was used next to two-photon excited Fluorescence Lifetime Imaging Microscopy (FLIM) to characterize the distribution of PCA on GO and rGO and compared to UV-vis and X-ray Photoelectron Spectroscopy (XPS) analysis of the materials. Raman imaging clearly highlights the difference in the spatial distribution of PCA molecules on GO and rGO. Two-photon excited FLIM helped in gaining insight into the elusive phenomena and effects occurring at the GO-PCA interface level. Apart from the charge transfer effects from PCA molecules to GO, the GO structure depends on the molecular orientation and the spatial distribution of PCA molecules identified by different sp2 network domains in Raman mapping. Heating of GO-PCA results in an enhancement of the sp2 network presumably as the PCA aromatic core becomes fused into the GO nanosheets whilst enriching the resulting rGO nanosheets with carboxyl functionalities. This "healing" effect observed in rGO-PCA might be of high importance for applications using rGO-PCA matrices and interfaces in particular for electrical devices.

EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL).

Electrowetting and droplet impalement experiments on superhydrophobic multiscale structures.

The reversible actuation of droplets on superhydrophobic surfaces under ambient conditions is currently an important field of research due to its potential applicability in microfluidic lab-on-a-chip devices. We have recently shown that Si-nanowire (NW) surfaces allow for reversible actuation provided that the surface structures show certain characteristics. In particular it appears that, for such surfaces, the presence of structures with multiple specific length scales is indeed needed to have a robust reversibility of contact angle changes. Here we report on electrowetting (EW) and impalement experiments on double-scale structured surfaces prepared by a combination of silicon micropillars prepared by an association of optical lithography and silicon etching, and nanowire growth on top of these surfaces. We show that while micropillar surfaces have a low impalement threshold and irreversible EW behaviour, a surface with double-scale texture can show both a very high resistance to impalement and a limited reversibility under EW, provided that the roughness of the micro-scale is large enough--i.e. that the pillars are tall enough. The optimal performance is obtained for a space between pillars that is comparable to the height of the nanostructure.

Molecular monolayers on silicon as substrates for biosensors.

(111) silicon surfaces can be controlled down to atomic level and offer a remarkable starting point for elaborating nanostructures. Hydrogenated surfaces are obtained by oxide dissolution in hydrofluoric acid or ammonium fluoride solution. Organic species are grafted onto the hydrogenated surface by a hydrosilylation reaction, providing a robust covalent Si-C bonding. Finally, probe molecules can be anchored to the organic end group, paving the way to the elaboration of sensors. Fluorescence detection is hampered by the high refractive index of silicon. However, improved sensitivity is obtained by replacing the bulk silicon substrate by a thin layer of amorphous silicon deposited on a reflector. The development of a novel hybrid SPR interface by the deposition of an amorphous silicon-carbon alloy is also presented. Such an interface allows the subsequent linking of stable organic monolayers through Si-C bonds for a plasmonic detection. On the other hand, the semiconducting properties of silicon can be used to implement field-effect label-free detection. However, the electrostatic interaction between adsorbed species may lead to a spreading of the adsorption isotherms, which should not be overlooked in practical operating conditions of the sensor. Atomically flat silicon surfaces may allow for measuring recognition interactions with local-probe microscopy.

Extreme resistance of superhydrophobic surfaces to impalement: reversible electrowetting related to the impacting/bouncing drop test.

The paper reports on the comparison of the wetting properties of superhydrophobic silicon nanowires (NWs), using drop impact impalement and electrowetting (EW) experiments. A correlation between the resistance to impalement on both EW and drop impact is shown. From the results, it is evident that when increasing the length and density of NWs (i) the thresholds for drop impact and EW irreversibility increase and (ii) the contact-angle hysteresis after impalement decreases. This suggests that the structure of the NW network could allow for partial impalement, hence preserving the reversibility, and that EW acts the same way as an external pressure. The most robust of our surfaces shows a threshold to impalement higher than 35 kPa, while most of the superhydrophobic surfaces tested so far have impalement thresholds smaller than 10 kPa.

Water exclusion at the nanometer scale provides long-term passivation of silicon (111) grafted with alkyl monolayers.

This work is a quantitative study of the conditions required for a long-term passivation of the interface silicon-alkyl monolayers prepared by thermal hydrosilyation of neat 1-alkenes on well-defined H-Si(111) surfaces. We present electrochemical capacitance measurements (C-U) in combination with ex situ atomic force microscopy (AFM) observations and X-ray photoelectron spectroscopy (XPS) measurements. Capacitance measurements as a function of the reaction time and XPS data reveal close correlations between the chemical composition at the interface and its electronic properties. A very low density of states is found if suboxide formation is carefully prevented. The monitoring of C-U plots and AFM imaging upon exposure of the sample in diverse conditions indicate that the initial electronic properties and structure of the interface are long-lasting only when the monolayer surface coverage is theta > 0.42. A model demonstrates that this threshold value corresponds to a monolayer with intermolecular channels narrower than approximately 2.82 A, which is equal to the diameter of a water molecule. Water exclusion from the monolayer promotes long-term passivation of the silicon surface against oxidation in air and water as well as perfect corrosion inhibition in 20% NH(4)F. We provide two criteria to assess when a sample is optimized: The first one is an effective dielectric constant <2.5, and the second one is a very characteristic energy diagram at open circuit potential.